Car interior member and molding method of the same

Abstract: A car interior member and its molding method are offered to improve recycling and to reduce the number of parts. The instrument panel (10) as the car interior member is made by molding integrally the core member (11) organizing the main structure of certain area of car interior and the functional member (12,13,14) having particular function and attached to the core member (11) by the blow molding. The number of parts can be more reduced when the base layer placed on the most inside, the foamed layer and the surface layer placed on the most outside of the member are molded by a multilayer blow molding in case of the instrument panel (10) formed with the multi-layer construction.

Description: This invention relates to a car interior member and its molding method, and intends particularly to be used to mold an instrument panel in front area of the car, a rear-board unit in rear area of the car, a door trim, a console unit, a head rest, a trunk-room unit and various lids. Conventionally, the car interior members such as the instrument panel have been advancing in resinification to comply with requirements of moldability, free in shape, design, corrosion resistance and weight saving, and more particularly, a polyolefin resin material such as polypropylene has been employed to satisfy requirement of high-temperature properties and stiffness properties for the car interior member. The car interior member, especially the instrument panel, is provided with a lot of functional parts held some functions such as ducts and meter clusters, and its shape is rather complicated. Accordingly, under the present circumstances, a core member and every functional member defining the car interior member are separately formed, and then the car interior member can be assembled with the separately prepared parts. The above polyolefin resin material such as polypropylene used in many cases as the car interior member is not applicable in a large-scale blow molding because of a dissatisfactory blow moldability such as drawdown resistance. Therefore, an external appearance of a molding tends to be inferior even if the drawdown resistance is improved by an increase of molecular weight. Accordingly, the blow molding has been applied limitedly to members not exposing from surface of the car interior which does not require a satisfaction on an external appearance, and comparatively small functional member. Fig. 8 depicts a molding method for an instrument panel 90 as an example of conventional molding method for the above described car interior member. The instrument panel 90 is arranged with a core member 91 forming main structure of the front area of the car interior, a duct 92 as functional member applied in the core member 91, a meter cluster 93 and a surface member 94. The core member 91 is formed by an injection molding with a denatured substance of PPO (polyphenylene oxide) (Trademark; "NORIRU"), PPF (filler filled polypropylene), or PPG (glassfibre fitted polypropylene). The duct 92 is provided for an air-conditioning, heater, defroster received in the core member 91 and is formed by the blow molding with PP (polypropylene), or PP/EPR (polypropylene/ethylene propylene rubber). The meter cluster 93 is a member surrounding several meters such as a speed meter and is formed by an injection molding with ABS (acrylonitrile butadiene styrene), a denatured substance of PPO (polyphenylene oxide) (Trademark; "NORIRU"), or PPF (filler filled polypropylene). The surface member 94 is to be the most outside of the instrument panel 90, and is defined by a surface layer made from PVC (polyvinylchloride) and a foamed layer made from foaming urethane and laminating inside of the surface layer by mean of a slash molding or a thermoforming. The instrument panel 90 is assembled with the members formed individually with respective materials and by different molding methods. However, in the conventional molding method for the car interior member like the molding method for the instrument panel 90 depicted in above Fig. 8, number of parts has been increased to form individually the core member composing the main structure in certain area of the car interior and the functional member having particular function attached in the core member. Therefore, costs for material, die, molding apparatus for every member were expensive. Manufacture took much time because the process of molding for every member and the process of assembling every member are required when the car interior member has been manufactured. It was also difficult to recycle because individually formed members have been made from different materials and all members have not been able to be recycled all together. In case of recycling, a necessity of frequent process and cost for collecting parted members was subject matter. The present invention has an object to supply the car interior member and its molding method that can reduce number of parts and improve recycling. EP-A-274535 discloses a car interior member, comprising: an elongate hollow core member providing a main structure of certain area of car interior, and at least one integral elongate functional member having a particular function. According to a first aspect of the present invention such a member is characterised in that the car interior member is formed by blow molding in such a way that the interior walls of the car interior member join along at least one longitudinally extending line (E) thereby forming at least two substantially fully enclosed longitudinally extending hollow ducts one of which provides the core member and at least one of which provides the or each functional member. EP-A-274535 discloses a method of molding a hollow car interior member, comprising the step of blow molding the car interior member to form integrally an elongate core member providing a main structure of certain area of car interior and at least one elongate functional member having a particular function. According to a second aspect of the present invention, such a method is characterised in that the car interior member is blow molded in such a way that the interior walls of the core and interior member join along at least one longitudinally extending line (E) thereby forming at least two substantially fully enclosed longitudinally extending hollow ducts one of which provides the core member and at least one of which provides the or each functional member. Preferably the core member and the functional member have an innermost base layer and an outermost surface layer, the two layers being simultaneously molded with a multilayer blow molding. Preferably a foamed layer is provided between the base layer and surface layer, the three layers being simultaneously molded with the multilayer blow molding. Preferably all of the layers are made from a polyolefin resin material. Preferably part of the member is an instrument panel. In the accompanying drawings: Figure 1 is a front view of appearance of the first embodiment for the present invention; Figure 2 is a back view of the above embodiment; Figure 3 is a sectional view of the point A in Figures 1, 2 of the above embodiment; Figure 4 is a sectional view of the point B in Figures 1, 2 of the above embodiment; Figure 5 is a sectional view of the point C in Figures 1, 2 of the above embodiment; Figure 6 is a sectional view of the point D in Figures 1, 2 of the above embodiment; Figure 7 is an enlarged view of a part of Figure 3 of the above embodiment; and Figure 8 is a perspective view of an entire appearance of a conventional embodiment. The preferred embodiment of the present invention will no be described with reference to the drawings. From Fig. 1 to Fig. 7 depict an instrument panel 10 as the interior member relating with this embodiment. Fig. 1 depicts a front view (view of looking from the driver's seat) of the instrument panel 10, Fig. 2 depicts a back view, Fig. 3, 4, 5, 6 depict sectional views at points of A, B, C, D in Fig 1, 2, and Fig. 7 depicts enlarged view of a part of Fig. 3. In those drawings, the instrument panel 10 provides a hollow main body 11 which is formed with a curved plate member 20 (see Fig. 7), a meter cluster section 12 which is formed as a part of the main body 11 is indented on the inside for laying every meter, a duct 13 for car interior temperature control formed on the inside of the main body 11 and a duct 14 for defroster to defrosting. The ducts 13, 14 hold blast nozzle 15, 16 which are placed in front of the instrument panel 10 (on the side of the driver's seat) to blast every gas for the defroster or for the car interior temperature control to inside of the car or a wind shield, and supply duct 17, 18 placed on back side to supply above gas into the duct 13, 14. The main body 11 applies to the core member and part of the functional member, and the meter cluster 12 and the ducts 13, 14 apply to the functional member. In Fig. 7, a plate member 20 forming every part of the instrument panel 10 holds a three layer structure which are a base layer 21 in the most inside, a foamed layer 22 placed outside of the base layer 21 and a surface layer 23 of the most outside (side of surface), and the three layers are simultaneously formed by a multilayer blow molding. The base layer 21 is made from polyolefin resin material or better made from polypropylene resin material, and might be composed of the polypropylene resin material and inorganic filler (talc, mica, calcium carbonate and others), glass fiber or rubber (much more olefin rubber) to improvement of high-impact properties. The base layer 21 keeps a shape of the instrument panel 10 and bestows mechanical properties of stiffness properties or high-impact properties. A thickness of the base layer 21 is 1-15 mm or much better 2-10 mm. Desirable instances of concrete organization of component of the base layer 21 are enumerated (A) propylene-ethylene block copolymer 66-99 weight % in melt index less 1.0 g/10 min. and in isotacticpentad index of propylene homopolymer more 90 mole %, (B) high-density polyethylene 5-30 weight % in melt index less 0.1 g/10 min., (C) rubber-like polymer 10-30 weight %, (D) inorganic filler 5-30 weight %, that has average particle diameter less 10µm in a powder or a fiber state. By using the blow molding resin material including above (A), (B), (C), (D), the large blow molding can be facilitated, and satisfying molding products in external appearance and mechanical properties can be obtained. The surface layer 23 is made from the polyolefin resin material which is capable of using polyolefin resin such as polyethylene, polypropylene and polybutene-1 or a polyolefin type rubber such as ethylene-propylene copolymer rubber and ethylene-propylene-diene copolymer rubber as material, and composition or cross linking of the above materials or mixture of various filler and the above materials might be possible. The surface layer 23 bestows the design, the sense of quality, the sense of touch and the sense of luxury. A thickness of the surface layer 23 is 0.5-10 mm, or 1-5 mm in desired. The foamed layer 22 is made from foamed the polyolefin resin material which is capable of using polyolefin resin such as polyethylene, polypropylene and polybutene-1, polyolefin rubber such as ethylene-propylene copolymer rubber and ethylene-propylene-diene copolymer rubber or the composition or the cross linking of the above material. Thermoplastic olefin elastomer (TPO) satisfies and more than satisfaction is thermoplastic olefin elastomer (TPO) blended polyolefin type rubber such as ethylene-propylene copolymer rubber and ethylene-propylene-diene copolymer rubber. The foamed layer 22 bestows the sound insulation, the deluxe sound on tapping and the damping on the instrument panel 10. A thickness of the foamed layer 22 is 1-5 mm, and in likely 2-10 mm. Satisfying instance of concrete component of the foamed layer 22 is enumerated thermoplastic olefin elastomer with ethylene content 5-30 weight % within the range of isotactic index 50-90 % by a boiling n-heptane extraction and the range of melt index 0.1-5g per 10 min. In this case, more than the above range of melt index is not preferable because foaming up ratio is insufficient for low viscosity on making the foamed layer, and less than the above range is not preferable because a flow characteristics is dissatisfied on forming. More than the above range of the isotactic index is not adequate because a sense of soft touching is spoiled on completing the product, and less than the above range is not adequate because the foaming up ratio is insufficient for low viscosity. The foamed layer 22 can be reasonably used olefin copolymer rubber within the range of a mooney viscosity (ML 1+4 100°C) 40-90 with propylene content amount 45-70 weight %. Out above range of propylene content amount is not adequate because stiffness of rubber raises and then the sense of soft touching is spoiled on completing the product. Less than the above range of the mooney viscosity is not adequate for spoiling the sense of soft touching because stiffness properties and stiffness are increased by orientation which shear on forming easily forms orientation layer, and more than the above range is not adequate because the foaming up ratio is insufficient on making the foamed layer. The foamed layer 22 can be suitably used for blending above thermoplastic olefin elastomer and olefin copolymer rubber. A method of foaming in the foamed layer 22 is adopted to can make foam on forming to blend foaming agent in the range of decomposition temperature 150-250°C and resin composition 0.5-6 per weight. For example, 4 per weight of Polyethylene EE-207 (name of product), made by EIWA KASEI KOHGYOH, Inc., in decomposition temperature 210°C is blended as the foaming agent to make foam. In this embodiment, after performing a tubular parison which is made of the three layer of the base layer 21, the foamed layer 22 and the surface layer 23 by extrusion or injection, and the instrument panel 10 is formed with the parison which is inflated to blow air into the inner parison while clamping the parison in a die fitted a form of the product and then which is cool down and solidify. Because a part of the parison is secured with opposite another parison (E section in Fig. 7) when the parison is clamped in the die in the blow molding the duct 13, 14 are formed to use of inner space of the instrument panel 10. The blast nozzle 15, 16 and the supply duct 17, 18 of the duct 13, 14 are formed to cut a part of the plate member which after cool down and solidify. The instrument panel 10 can be molded by usual blow molding method, and a instance of molding condition is enumerated to can be molded in screw 90 mm, die 300 mm, temperature resin 200-240 °C and mold temperature 28 °C for using a blow molding machine 90 mm made by ISHIKAWAJIMA HARIMA KOHGYOH, Inc., Following effectiveness is in the embodiment. The main body 11 of the instrument panel 10, the meter cluster 12 and duct 13, 14 are integrally molded with the blow molding, and the base layer 21, the foamed layer 22 and the surface layer 23 are simultaneously molded with the multilayer blow molding, therefore on the current, the number of parts can be retrenched to all integrally mold the core member 91 arranged the current instrument panel 90 in Fig. 8 and the functional member which is assigned as the duct 92, the meter cluster 93 and the surface member 94. And materials, dies, molding apparatus and others to use for molding can be retrenched, and management of members can be easy. A process of molding can be retrenched on the occasion of manufacturing the instrument panel 10 with fewer number of parts, and also a process of assembly can be unnecessary, The plate member 20 forming the instrument panel 10 includes the foamed layer 22 can bestow the sound insulation, the noble sound on tapping and the damping on the instrument panel 10 and concurrently the foamed layer 22 is simultaneously molded with the base layer 21 and the surface layer 23 by the multilayer blow molding, so that increase of number of parts with the foamed layer 22 can be prevented. All of the base layer 21, the foamed layer 22 and the surface layer 23 are molded with the polyolefin resin material, therefore collective recycling and a work recycling can be easier. The duct 13, 14 forming for using inner space of the instrument panel 10 can make number of part of the instrument panel 10 retrench and can make inside structure of the instrument panel 10 simplify. The present invention is not restricted within the above embodiment, but also other component to can realize the object of the present invention is included, that is following transformation is included in the present invention. In the present invention, the plate member 20 forming the instrument panel 10 includes the foamed layer 22, but the structure with the base layer 21 and the surface layer 23 exclude the foamed layer 22 might be possible. It is preferable however, to provided the foamed layer 22 to can be bestowed the sound insulation, the noble sound on tapping and the damping on the instrument panel 10. The three layers of the base layer 21, the foamed layer 22 and the surface layer 23 are simultaneously formed with multilayer blow molding in the above embodiment, but the base layer 21 is molded with the single layer blow molding and then the foamed layer 22 and the surface layer 23 might be adhered to such base layer 21, or the base layer 21 and the foamed layer 22 which are first simultaneously molded with the multilayer blow molding might be adhered to the surface layer 23, in short, the base layer 21 has to be molded with the blow molding All of the three layers, however, are simultaneously molded with the multilayer blow molding to can scheme fewer number of parts. The main body 11 of the instrument panel 10, the meter cluster 12 and the duct 13, 14 are integrally molded with the blow molding in the above embodiment, but it is unnecessary to integrally mold all functional member, that is, the duct 13, 14 and the main body 11 are integrally molded and the meter cluster 12 might be another member as in the past. As many as possible of, desiring all of the functional member and the main body are integrally molded to can more scheme fewer number of parts. All three layer of the base layer 21, the foamed layer 22 and the surface layer 23 are molded with the polyolefin resin material, but all layers are unnecessary to mold with the polyolefin resin material. All layers which are molded with the polyolefin resin material, however, are desired because recycling can be collectively effected and the work recycling can be easy. The material of the base layer 21, the foamed layer 22 and the surface layer 23 is not restricted to the polyolefin resin material but is volunteered in case of the thermoplastic resin material for using the blow molding. The structure that the instrument panel 10 holds the meter cluster 12, the duct 13, 14 and other is not necessarily always, for example, the instrument panel 10 might hold other functional member such as a gloved box unit and other. The car interior member is assigned as the instrument panel 10 in the above embodiment, and in the present invention other interior member in the car such as the rear-board unit, the door trim, the console unit, the head rest, the trunk-room unit and every lid can be accepted the application. Following comparative experiments were effected for ascertaining effect on the present invention. Experiment 1-6 that were prepared as an instrument panel holding integral structure by the blow molding in the embodiment of the present invention and comparison 1-3 that were prepared as an instrument panel holding usual divided structure against the experiment 1-6 were compared about every performance and function. In the experiment 1, 2, only the base layer 21 was molded with the single layer blow molding and was adhered to the surface layer 23. The foamed layer 22 was not provided. In the experiment 1, the base layer 21 was assigned as mixture that was propylene-ethylene block copolymer 70 weight % (melt index 0.57g/10 min., ethylene content 1.9 weight %, isotacticpentad index 92 mole % ), high-density polyethylene 10 weight % (melt index 0.03 g/10 min.), ethylene-propylene copolymer rubber 10 weight % (mooney viscosity [ML 1+4 100°C] =70, propylene content 27 weight % ), and talc 10 weight % (an average diameter of grain 1.5 micron). The surface was assigned as thermoplastic olefin elastomer with ethylene content 25 weight % in range within isotactic index 60 weight % for the boiling n-heptance extraction method and melt index 0.5g per 10 min. In the experiment 2, the base layer 21 was used glass fiber of diameter 13 µm instead of talc in the base layer 21 of the experiment 1. And, the surface layer 23 was assigned as the same of the experiment 1. In the experiment 3-6, the three layer of the base layer 21, the foamed layer 22 and the surface layer 23 were molded with the multilayer blow molding. In the experiment 3, the base layer 21 was used of high density polyethylene in density 0.950 g/cm 2 and melt index 0.03 g per 10 min. And the surface layer 23 was assigned as the same of the experiment 1. The foamed layer 22 was assigned as a composition that was thermoplastic olefin elastomer 50 weight % (ethylene content 25 weight %, isotactic index 60% by the boiling n-heptane extraction method, melt index 0.5 g/10 min.), and ethylene-propylene copolymer rubber 50 weight % (propylene content 65 weight %, mooney viscosity [ML 1+4 100°C] =76). In the experiment 4, the base layer 21 was assigned as propylene-ethylene block copolymer (ethylene content 1.9 weight %, melt index o.57 g/10 min., isotacticpentad index 92 mole %). The surface layer 23 and the foamed layer 22 were assigned as the same of the experiment 3. In the experiment 5, the base layer 21 was assigned as the same of the experiment 1. The surface layer 23 and the foamed layer 22 were assigned as the same of the experiment 3. In the experiment 6, the base layer 21 was assigned as the same of the experiment 2. The surface layer 23 and the foamed layer 22 were assigned as the same of the experiment 3. In the comparison 1, all of the core member 91 in Fig. 3 and other functional member were made by injection molding with PPF, and the surface member 94 (the foamed layer and the surface layer) was not provided. In the comparison 2, 3, after the core member 91 and other functional member were molded with transformed thing (the name of product, NORIRU) of PPO (polyphenylene oxide), PPF (filler filled polypropylene), and PPG (filled polypropylene glassfiber) the surface member 94 (the foamed layer and the surface layer) was provided. The surface layer was made from PVC (polyvinyl chloride) and the foamed layer was made from urethane foam. The surface member 94 was placed on the part of the surface instrument panel in the comparison 2, and in the comparison 3 the surface member 94 was placed on whole surface instrument panel. Following are ways of evaluation of every performance and function for the experiment 1-6 and the comparison 1-3. About the sense of touch, ○ meant case of having feeling of pliant (feeling of soft) on touching by hand and having the sense of expansiveness in bass on tapping, X meant case of having cheaply feet for a high tone on tapping and ▵ meant case of feeling middle of ○ and X. About sound insulation, under condition of sound 103 dB in the engine room, loudness was measured in the inside in the car when every instrument panel was simply provided. About damping, X meant case of generating strange oscillatory sound or clear damage of the product, ○ meant in level of standing for nothing unusualness when oscillation in cycle 30 Hz was gained 10 7 times with situated an excitation machine in state of usually providing every instrument panel. About high-temperature properties, every instrument panel was left alone for a half hour in room temperature after keeping for four hours under fixed atmosphere temperature, and then injurious transformation, stickiness on the surface and yes or no of unusualness such as a damage and a fault hindering to usual operating were ascertained. The highest temperature by appearing unusualness was measured to let temperature change for such action. Table 1 is shown results of the comparative experiments. The experiment 3-6 result in possible recycling number of parts is one because of the multilayer blow molding of the three layer and in excellent performance of others. In the experiment 1, 2 the surface layer 23 is adhered later so that number of parts is two in more than the experiment 3-6 but less than as in the past, and recycling is made possible. In opposition, the comparison 1 is made possible to recycle for one sort of material, but is held a lot of number of parts and fault performance of others. The comparison 2, 3 bestow the sense of luxury to provide the surface 94 (foamed layer and surface layer) but hold a lot of number of parts and can not recycle to a lot of kind of materials. Effectiveness of the present invention was conspicuously shown from above comparative experiments. As the foregoing description of the present invention, it is effect of being able to reduce number of parts and to develop recycling because the core member and every functional member arranged the car interior member are integrally molded with the blow molding.

Claims: A car interior member, comprising: an elongate hollow core member (11) providing a main structure of certain area of car interior, and at least one integral elongate functional member (13,14) having a particular function; characterised in that the car interior member is formed by blow molding in such a way that the interior walls of the car interior member join along at least one longitudinally extending line (E) thereby forming at least two substantially fully enclosed longitudinally extending hollow ducts one of which provides the core member (11) and at least one of which provides the or each functional member (13,14). A car interior member according to claim 1, wherein the functional member (13,14) is an air duct for defrosting air. A car interior member according to claim 1, wherein the functional member (13,14) is an air duct for controlling the car interior temperature. A method of molding a hollow car interior member, comprising the step of blow molding the car interior member to form integrally an elongate core member (11) providing a main structure of certain area of car interior and at least one longitudinally extending functional member (13,14) having a particular function; characterised in that the car interior member is blow molded in such a way that the interior walls of the core and interior member join along at least one longitudinally extending line (E) thereby forming at least two substantially fully enclosed longitudinally extending hollow ducts one of which provides the core member (11) and at least one of which provides the or each functional member (13,14). A method according to claim 4, wherein the core member (11) and the functional member (13,14) have an innermost base layer (21) and an outermost surface layer (23), the two layers being simultaneously molded with a multilayer blow molding. A method according to claim 5, wherein a foamed layer (22) is provided between the base layer (21) and surface layer (23), the three layers being simultaneously molded with the multilayer blow molding. A method according to any one of claims 4 to 6, wherein all of the layers (21,22,23) are made from a polyolefin resin material. A method of molding car interior member according to any one of claims 4 to 7, wherein part of the member is an instrument panel.

Inventors: HIRANO KOKI, NAKAMURA TETSUYA, SUGAWARA MINORU, TADA KATSUHIKO, HIRANO, KOKI, NAKAMURA, TETSUYA, SUGAWARA, MINORU, TADA, KATSUHIKO, HIRANO, KOKI, C/O IDEMITSU PETROCH. CO., LTD., NAKAMURA, TETSUYA, C/O IDEMITSU PETROCH. CO., LTD., SUGAWARA, MINORU, C/O IDEMITSU PETROCH. CO., LTD., TADA, KATSUHIKO, C/O IDEMITSU PETROCH. CO., LTD.
Applicants: IDEMITSU PETROCHEMICAL CO, IDEMITSU PETROCHEMICAL CO. LTD.
Application year: 1994
Main classification: B60K37
IPC codes: B60K37, B29C49, B60H1, B62D29